This Dec. 2, 2016, view from the Navigation Camera (Navcam) on the mast of NASA's Curiosity Mars Rover shows rocky ground within view while the rover was working at an intended drilling site called "Precipice" on lower Mount Sharp.

A NASA radio on Europe's Trace Gas Orbiter, which reached Mars in October 2016, has succeeded in its first test of receiving data from NASA Mars rovers, both Opportunity and Curiosity. This graphic depicts the geometry of the relay from Opportunity to the orbiter, which then sent the data to Earth.

The dark, smooth-surfaced rock at the center of this Oct. 30, 2016, image from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover was examined with laser pulses and confirmed to be an iron-nickel meteorite. It is about the size of a golf ball.

The dark, golf-ball-size object in this composite, colorized view from the ChemCam instrument on NASA's Curiosity Mars rover is a nickel-iron meteorite, as confirmed by analysis using laser pulses from ChemCam on Oct. 30, 2016. The grid of bright spots on the rock resulted from the laser pulses.

This September 2016 self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Quela" drilling location in the scenic "Murray Buttes" area on lower Mount Sharp. The panorama was stitched together from multiple images taken by the MAHLI camera at the end of the rover's arm.

This 360-degree panorama was acquired on Sept. 4, 2016, by the Mast Camera on NASA's Curiosity Mars rover while the rover was in a scenic area called "Murray Buttes" on lower Mount Sharp. The flat-topped mesa near the center of the scene rises to about 39 feet above the surrounding plain.

This map shows the route driven by NASA's Curiosity Mars rover from the location where it landed in August 2012 to its location in September 2016 at "Murray Buttes," and the path planned for reaching destinations at "Hematite Unit" and "Clay Unit" on lower Mount Sharp.

This graphic maps locations of the sites where NASA's Curiosity Mars rover collected its first 18 rock or soil samples for laboratory analysis inside the vehicle. It also presents images of the drilled holes where 14 rock-powder samples were acquired, most recently at "Quela," on Sept. 18, 2016.

The top of the butte in this Sept. 1, 2016, scene from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover stands about 16 feet above the rover and about 82 feet east-southeast of the rover. The site is in the "Murray Buttes" area of lower Mount Sharp, and this particular butte is called "M9a."

The mesa in the center of this scene from the "Murray Buttes" area on Mars is longer than a football field. The panorama combines images taken by the Mastcam on NASA's Curiosity Mars rover on Aug. 22 and Aug. 23, 2016.

The two prominent mesas in this Aug. 18, 2016, view of Mars' "Murray Buttes" region from the Curiosity Mars rover's Mastcam are about 260 feet (about 80 meters) apart. The one on the right is about 33 feet high, and its top is about 270 feet from the rover's position when the images were taken.

Apollo 11 astronaut Buzz Aldrin, left, and Erisa Hines of NASA's Jet Propulsion Laboratory in Pasadena, California, speak to members of the news media during a preview of the new "Destination: Mars" experience at the Kennedy Space Center visitor complex in Florida.

This 360-degree vista was acquired on Aug. 5, 2016, by the Mastcam on NASA's Curiosity Mars rover as the rover neared features called "Murray Buttes" on lower Mount Sharp. The dark, flat-topped mesa seen to the left of the rover's arm is about 50 feet high and, near the top, about 200 feet wide.

This July 22, 2016, stereo scene from the Mastcam on NASA's Curiosity Mars Rover shows boulders at a site called "Bimbe" on lower Mount Sharp. They contain pebble-size and larger rock fragments. The image appears three dimensional when viewed through red-blue glasses with the red lens on the left.

This 360-degree vista was acquired on Aug. 5, 2016, by the Mastcam on NASA's Curiosity Mars rover as the rover neared features called "Murray Buttes" on lower Mount Sharp. The dark, flat-topped mesa seen to the left of the rover's arm is about 50 feet high and, near the top, about 200 feet wide.

NASA's Curiosity Mars rover began close-up investigation of a target called "Marimba," on lower Mount Sharp, during the week preceding the fourth anniversary of the mission's Aug. 6, 2016, landing. Curiosity's Navigation Camera took this shot of the rover's arm over Marimba on Aug. 2, 2016.

NASA's Curiosity Mars rover autonomously selects some targets for the laser and telescopic camera of its ChemCam instrument. For example, on-board software analyzed the Navcam image at left, chose the target indicated with a yellow dot, and pointed ChemCam for laser shots and the image at right.

Two sizes of ripples are evident in this Dec. 13, 2015, view of a top of a Martian sand dune, from NASA's Curiosity Mars rover. Sand dunes and the smaller type of ripples also exist on Earth. The larger ripples are a type not seen on Earth nor previously recognized as a distinct type on Mars.

This scene shows NASA's Curiosity Mars rover at a location called "Windjana," where the rover found rocks containing manganese-oxide minerals, which require abundant water and strongly oxidizing conditions to form.

This graphic maps the first 14 sites where NASA's Curiosity Mars rover collected rock or soil samples for analysis using the rover's onboard laboratory. It also presents images of the drilled holes where 12 rock-powder samples were acquired. At the other two sites Curiosity scooped soil samples.

The top of the rover's mast faces away in this May 11, 2016, self-portrait of NASA's Curiosity Mars rover, which shows the vehicle at the "Okoruso" drilling site on lower Mount Sharp. The scene is a mosaic of multiple images taken with the arm-mounted Mars Hands Lens Imager (MAHLI).7856

This May 11, 2016, self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Okoruso" drilling site on lower Mount Sharp's "Naukluft Plateau." The scene is a mosaic of multiple images taken with the arm-mounted Mars Hands Lens Imager (MAHLI).

This animated image blinks two versions of a May 11, 2016, selfie of NASA's Curiosity Mars rover at a drilled sample site called "Okoruso." In one version, cameras atop the rover's mast face the arm-mounted camera taking the portrait. In the other, they face away.

NASA's Curiosity Mars rover measures the concentration of methane in the atmosphere at Gale Crater. A one-time spike in methane, up to about 7 parts per billion occurred during Curiosity's first Martian year. Variations in much lower background levels of methane may be seasonal.

By monitoring weather through two Martian years since landing in Gale Crater, NASA's Curiosity Mars rover has documented seasonal patterns in variables such as temperature, water-vapor content and air pressure. Each Mars year lasts nearly two Earth years.

By monitoring weather through two Martian years since landing in Gale Crater, NASA's Curiosity Mars rover has documented seasonal patterns in variables such as temperature, water-vapor content and air pressure. Each Mars year lasts nearly two Earth years.

This early-morning view from the Mastcam on NASA's Curiosity Mars rover on March 16, 2016, covers a portion of the inner wall of Gale Crater. At right, the image fades into glare of the rising sun. Details such as gullies and debris fans help geologists understand processes that shaped the crater.

This 360-degree panorama from the Mastcam on NASA's Curiosity Mars rover shows the rugged surface of 'Naukluft Plateau' plus upper Mount Sharp at right and part of the rim of Gale Crater. The April 4, 2016, scene is dominated by eroded remnants of a finely layered ancient sandstone deposit.

This 360-degree panorama from the Mastcam on NASA's Curiosity Mars rover shows the rugged surface of 'Naukluft Plateau' plus upper Mount Sharp at right and part of the rim of Gale Crater. The April 4, 2016, scene is dominated by eroded remnants of a finely layered ancient sandstone deposit.

The nodule in the center of this March 10, 2016, image from the Mars Hand Lens Imager (MAHLI) on NASA's Curiosity Mars rover shows individual grains of sand and (on the right) laminations from the sandstone deposit in which the nodule formed..

Patches of Martian sandstone visible in the lower-left and upper portions of this view from the Mast Camera (Mastcam) of NASA's Curiosity Mars rover have a knobbly texture due to nodules apparently more resistant to erosion than the host rock in which some are still embedded.

Patches of Martian sandstone visible in the lower-left and upper portions of this view from the Mast Camera (Mastcam) of NASA's Curiosity Mars rover have a knobbly texture due to nodules apparently more resistant to erosion than the host rock in which some are still embedded.

This map shows the route driven by NASA's Curiosity Mars rover from where it landed in 2012 to its location in early March 2016, approaching 'Naukluft Plateau.' As the rover continues up Mount Sharp, its science team has been refreshed by a second round of NASA participating-scientist selections.

The Mars Hand Lens Imager (MAHLI) camera on the robotic arm of NASA's Curiosity Mars rover used electric lights at night on Jan. 22, 2016, to illuminate this postage-stamp-size view of Martian sand grains dumped on the ground after sorting with a sieve.

This Jan. 19, 2016, self-portrait of NASA's Curiosity Mars rover shows the vehicle at "Namib Dune," where the rover's activities included scuffing into the dune with a wheel and scooping samples of sand for laboratory analysis.

This Dec. 18, 2015, view of the downwind face of "Namib Dune" on Mars covers 360 degrees, including a portion of Mount Sharp on the horizon. The component images were taken by the Mast Camera on NASA's Curiosity Mars rover. The site is part of the dark-sand "Bagnold Dunes" field of active dunes.

This Dec. 17, 2015, view combines multiple images from the telephoto-lens camera of the Mast Camera (Mastcam) on NASA's Curiosity Mars rover to reveal fine details of the downwind face of "Namib Dune." Sand on this face of the dark dune has cascaded down a slope of about 26 to 28 degrees.

This stereo view from NASA's Curiosity Mars Rover shows the downwind side of a dune about 13 feet high within the Bagnold Dunes on Mars. The image appears three-dimensional when viewed through red-blue glasses with the red lens on the left. Curiosity's Navcam took the component images on Dec. 17, 2015.

This view from NASA's Curiosity Mars Rover shows the downwind side of a dune about 13 feet high within the Bagnold Dunes field on Mars. The rover's Navigation Camera took the component images on Dec. 17, 2015. As on Earth, the downwind side of an active sand dune has a steep slope called a slip face.

This view from NASA's Curiosity Mars Rover shows the downwind side of a dune about 13 feet high within the Bagnold Dunes field on Mars. The rover's Navigation Camera took the component images on Dec. 17, 2015. As on Earth, the downwind side of an active sand dune has a steep slope called a slip face.

This graph shows the ratio of concentrations of several elements in four different pairs of targets examined by Alpha Particle X-ray Spectrometer (APXS) instruments on NASA Mars rovers Curiosity and Spirit.

NASA's Curiosity Mars rover examined both the "Greenhorn" and "Big Sky" targets with the rover's Alpha Particle X-ray Spectrometer (APXS) instrument. Greenhorn is located within an altered fracture zone and has an elevated concentration of silica (about 60 percent by weight). Big Sky is the unaltered counterpart for comparison.

The yellow triangles on this graph indicate concentrations of the elements titanium and silicon in selected rock targets with high silica content analyzed by the Alpha Particle X-ray Spectrometer (APXS) instrument on NASA's Curiosity rover in Mars' Gale Crater.

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover covers an area in "Bridger Basin" that includes the locations where the rover drilled a target called "Big Sky" on the mission's Sol 1119 (Sept. 29, 2015) and a target called "Greenhorn" on Sol 1137 (Oct. 18, 2015).

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover covers an area in "Bridger Basin" that includes the locations where the rover drilled a target called "Big Sky" on the mission's Sol 1119 (Sept. 29, 2015) and a target called "Greenhorn" on Sol 1137 (Oct. 18, 2015).

This image from NASA's Curiosity Mars rover reveals details of a bedrock discoloration pattern at a site between "Marias Pass" and "Bridger Basin." The discoloration is not associated with individual layers. It crosses layers and shows clear horizontal boundaries to the darker toned bedrock. This suggests it is related to alteration by fluids that flowed through fractures and permeated into the bedrock.

This view from NASA's Curiosity Mars rover shows an example of discoloration closely linked to fractures in the Stimson formation sandstone on lower Mount Sharp. The pattern is evident along two perpendicular fractures.

This image from the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity Mars rover shows detailed texture of a rock target called "Elk" on Mars' Mount Sharp, revealing laminations that are present in much of the Murray Formation geological unit of lower Mount Sharp.

NASA's Curiosity Mars rover used its Navigation Camera (Navcam) to capture this view partway back down a slope it climbed toward "Marias Pass" on lower Mount Sharp. The image was taken May 22, 2015. It includes a silica-rich target rock called "Elk."

This May 22, 2015, view from the Mast Camera (Mastcam) in NASA's Curiosity Mars rover shows the "Marias Pass" area where a lower and older geological unit of mudstone -- the pale zone in the center of the image -- lies in contact with an overlying geological unit of sandstone.

This May 22, 2015, view from the Mast Camera (Mastcam) in NASA's Curiosity Mars rover shows the "Marias Pass" area where a lower and older geological unit of mudstone -- the pale zone in the center of the image -- lies in contact with an overlying geological unit of sandstone.

This map shows the route on lower Mount Sharp that NASA's Curiosity followed between April 19, 2015, and Nov. 5, 2015. During this period the mission investigated silica-rich rock targets including "Buckskin," in the "Maria Pass" area, and "Greenhorn," in the "Bridger Basin" area.

This Dec. 5, 2015, view of the undisturbed surface of a Martian sand dune called "High Dune" shows coarse grains remaining on the surface after wind removal of smaller particles. The image covers an area 1.4 inches across. It was taken by the rover's Mars Hand Lens Imager (MAHLI).

This view shows grains of sand where NASA's Curiosity Mars rover was driven into a shallow sand sheet near a large dune. The scene covers an area 1.3 inches wide, imaged by Curiosity's Mars Hand Lens Imager on Dec. 3, 2015. Sunlight is coming from the left.

A wheel track left by NASA's Curiosity Mars rover exposes underlying material in a shallow sand sheet in this Dec. 2, 2015, view from Curiosity's Mast Camera (Mastcam). The site is close to a large sand dune of similarly dark sand grains.

The rippled surface of the first Martian sand dune ever studied up close fills this Nov. 27, 2015, view of "High Dune" from the Mast Camera on NASA's Curiosity rover. This site is part of the "Bagnold Dunes" field of active dark dunes along the northwestern flank of Mount Sharp.

The rippled surface of the first Martian sand dune ever studied up close fills this Nov. 27, 2015, view of "High Dune" from the Mast Camera on NASA's Curiosity rover. This site is part of the "Bagnold Dunes" field of active dark dunes along the northwestern flank of Mount Sharp.

The Mars Reconnaissance Orbiter took this photo of the Curiosity rover in September 2015, as Curiosity was exploring the boundary between two rock units: the light-toned Murray Formation and the overlying and darker-toned Stimson unit.

This graphic depicts paths by which carbon has been exchanged among Martian interior, surface rocks, polar caps, waters and atmosphere, and also depicts a mechanism by which it is lost from the atmosphere with a strong effect on isotope ratio.

JPL researchers Jessica Creamer, Fernanda Mora and Peter Willis (left to right) pose with the Chemical Laptop, a device designed to detect amino acids and fatty acids. At left is a near-identical copy of the Curiosity rover, which has been on Mars since 2012.

This Sept. 25, 2015, view from the Mast Camera on NASA's Curiosity Mars rover shows a dark sand dune in the middle distance. The rover's examination of dunes on the way toward higher layers of Mount Sharp will be the first in-place study of an active sand dune anywhere other than Earth.

The dark band in the lower portion of this Martian scene is part of the "Bagnold Dunes" dune field lining the northwestern edge of Mount Sharp. The scene combines multiple images taken with the Mast Camera on NASA's Curiosity Mars rover on Sept. 25, 2015. The view is toward south-southeast.

This view from the Mars Hand Lens Imager (MAHLI) on the arm of NASA's Curiosity Mars rover shows a combination of dark and light material within a mineral vein at a site called "Garden City" on lower Mount Sharp.

Light material emplaced within darker vein material is seen in this view of a mineral vein at the "Garden City" site on lower Mount Sharp, Mars. The Mars Hand Lens Imager (MAHLI) on the arm of NASA's Curiosity Mars Rover took the image on April 4, 2015. The area shown is roughly 0.4 inch wide.

These images and overlay bar charts from the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity Mars rover indicate where some high-potassium material is localized within mineral veins at "Garden City."-

Prominent mineral veins at the "Garden City" site examined by NASA's Curiosity Mars rover vary in thickness and brightness, as seen in this image from Curiosity's Mast Camera (Mastcam). The image covers and area roughly 2 feet across.

A view from the "Kimberley" formation on Mars taken by NASA's Curiosity rover. The strata in the foreground dip towards the base of Mount Sharp, indicating the ancient depression that existed before the larger bulk of the mountain formed.

Large-scale crossbedding in the sandstone of this ridge on a lower slope of Mars' Mount Sharp is typical of windblown sand dunes that have petrified. NASA's Curiosity Mars rover used its Mastcam to capture this vista on Aug. 27, 2015. Similarly textured sandstone is common in the U.S. Southwest.

This view of a test rover at NASA's Jet Propulsion Laboratory in California results from advance testing of arm positions and camera pointings for taking a low-angle selfie of NASA's Curiosity Mars rover. The rehearsal led to a dramatic Aug. 5, 2013, selfie of Curiosity by the rover's MAHLI camera.

Curiosity's DAN instrument for checking hydration levels in the ground beneath the rover detected an unusually high amount at a site near "Marias Pass," prompting repeated passes over the area to map the hydrogen amounts. This map shows color-coded results from multiple traverses over the area.